Soil Fumigation

1. Soil Fumigation Category E Turf and Ornamentals Pesticide Applicator Training Manual Chapter 12

2. Terms • Soil tilth—the degree to which a soil has been tilled. • Mycorrhizal fungi —beneficial microorganisms that transport minerals to the roots of plants and which can be killed by soil fumigation. Category E--- Chapter 12 Soil Fumigation

3. Introduction • Soil fumigants—volatile chemicals that, when injected into the soil, emit toxic fumes which penetrate the air spaces in sufficient concentration to kill living organisms. • Soil fumigants are extremely toxic and must not be inhaled.

4. Soil Fumigation Credit: University of California, Davis Credit: Smithsonian Magazine December 1996

5. Successful Soil Fumigation • Goals: • Safe and accurate application. • Rapid dissipation after completion. • Factors in successful fumigation: • Soil temperature between 60-80°F at 6 inch depth. • Soil moisture between 50-75% capacity. • Good soil tilth. • Proper selection of fumigant for the soil type. • Organic mater must be decomposed. • Seals—usually plastic tarps to prevent too-rapid escape of the fumigant. • Best time to apply—late summer or early fall. • Waiting period before planting—range 2 weeks to 2 months.

6. Soil FumigationSpecial Considerations • Temporary reduction of nitrifying bacteria in soil—can result in buildup of ammonium levels that could damage early crops. • Reduction of pests and predators. • Potential pest ‘rebound.’ • Mycorrhizal fungi will be killed—will take time to recolonize.